Determination of Phenolic Hydroxyl Groups in Technical Lignins by Ionization Difference Ultraviolet Spectrophotometry (∆ε-IDUS method)

Goldmann, Werner Marcelo; Ahola, Juha; Mankinen, Otto; Kantola, Anu M.; Komulainen, Sanna; Telkki, Ville‐Veikko; Tanskanen, Juha

doi:10.3311/ppch.9269

Cited by 21 publications

(21 citation statements)

References 22 publications

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“…4 Quantitative 13 C spectra of unmodified Indulin AT lignin (I2C) and its depolymerized product (M250C) after solvolysis in the macro reactor included in the determination of the phenolic hydroxyl content, the results of which are presented in Table 5. Overall, the obtained hydroxyl group contents for Indulin AT are in good agreement with our previous studies, where Indulin AT exhibited 1.66 mmol/g of α-OH, 0.98 mmol/g of β-OH, and 3.84 mmol/g of ϕ-OH [43].…”

Section: Nmr Analysis Of Upscaled Reactor Samplessupporting

confidence: 91%

“…Analysis of phenolic hydroxyl groups was carried out by Ultraviolet (UV) Spectrophotometry using a revised version of the previously reported Δε-IDUS method [43]. The samples were analyzed using quartz cuvettes with a 1 cm path-length in a Shimadzu 1800 double-beam spectrophotometer at wavelengths 300 and 360 nm.…”

Section: ∆ε-Idus Analysismentioning

confidence: 99%

“…Formaldehyde is able to react with phenolic structures in neighboring sites to the phenolic hydroxyl (-OH) [44]. In lignin, those neighboring sites can be occupied by methoxyl groups (-OMe or -OCH 3 ) as previously reported [43]. Thus, there were likely more of these aromatic methoxyl groups in the macro reactor lignin than in the semi-micro reactor lignin.…”

Section: Lignin Solvolysis In 1 L Reactormentioning

confidence: 99%

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Effect of Process Variables on the Solvolysis Depolymerization of Pine Kraft Lignin

Goldmann

Anthonykutty

Ahola

et al. 2019

Waste Biomass Valor

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Lignin modification opens the possibility of using it in polyol bio-based polymers, such as phenol-formaldehyde resins, polyurethanes, composites, and binders. Pine kraft lignin Indulin AT was partially depolymerized and the resulting products analyzed to determine their degree of valorization. Depolymerized lignin products were analyzed by GPC-SEC (molar mass), ∆ε-IDUS (phenolic hydroxyls), HACL (formaldehyde uptake), 13 C-NMR (hydroxyl and methoxyl groups), and 1 H-DOSY (molar mass distribution). The dominant parameter in lignin depolymerization by solvolysis was reaction temperature. According to the results, a higher reaction temperature decreases the average molar masses and PDI of lignin as well as the primary and secondary aliphatic hydroxyls, while simultaneously increasing the phenolic hydroxyls and formaldehyde uptake of lignin. Other variables (time, formic acid wt %, ethanol wt %, lignin load) had lesser effects. Partial depolymerization by solvolysis in mild conditions without catalyst is a viable valorization route for lignin, by which lignin properties can be significantly improved.

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Section: Nmr Analysis Of Upscaled Reactor Samplessupporting

confidence: 91%

Section: ∆ε-Idus Analysismentioning

confidence: 99%

Section: Lignin Solvolysis In 1 L Reactormentioning

confidence: 99%

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Effect of Process Variables on the Solvolysis Depolymerization of Pine Kraft Lignin

Goldmann

Anthonykutty

Ahola

et al. 2019

Waste Biomass Valor

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“…Difference UV spectrophotometry is a sample method used to determine the content of phenolic hydroxyls in lignin. This method is mainly based on the dissociation of phenolic hydroxyl in alkaline solution [34,35]. A sample of 10–15 mg of lignin was weighted and dissolved in 10 mL of dioxane, and a 2 mL solution was expanded to 50 mL by using a NaH 2 PO 4 /NaOH buffer solution (pH = 6) and a 0.2 mol/L sodium hydroxide solution.…”

Section: Methodsmentioning

confidence: 99%

Green Modification of Corn Stalk Lignin and Preparation of Environmentally Friendly Lignin-Based Wood Adhesive

Wang

2018

Polymers

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In this study, corn stalk lignin was used to react with non-volatile and non-toxic glyoxal under the catalysis of a sodium hydroxide solution, and a wood adhesive based on glyoxalated corn stalk lignin was prepared. The effect of the hydroxylation reaction on the structure and properties of lignin were studied using Fourier transform infrared spectroscopy (FTIR), ultraviolet spectrophotometry (UV), thermogravimetric analysis (TGA), titration tests, gel permeation chromatography (GPC), and differential scanning calorimetry (DSC). Compared with unmodified lignin, the glyoxalated corn stalk lignin had a significant improvement in hydroxyl content, activation, and thermal stability. At the same time, results from the GPC showed that the molecular weight increased compared with original corn stalk, possibly due to the secondary polycondensation reaction between lignin and glyoxal. Lignin-based environmental wood adhesives were prepared by mixing modified lignin and epichlorohydrin (ECH), and the dry strength of plywood reached 1.58 MPa. The mechanical strength and water resistance of plywood was improved significantly by mixing some aqueous emulsion into lignin-based adhesives, e.g., polyacrylic ester (AE) emulsion and aqueous polyurethane (PU) emulsion.

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“…It should be noted that the different functional groups have different reactivities. The amount of hydroxyl groups (-OH), particularly phenolic-hydroxyls, is one of the most important parameters in lignin because it is an indicator of lignin reactivity and give lignin its potential to be utilized in a variety of technical applications [ 69 ].…”

Section: Structure and Propertiesmentioning

confidence: 99%

Insights into the Potential of Hardwood Kraft Lignin to Be a Green Platform Material for Emergence of the Biorefinery

et al. 2020

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Lignin is an abundant, renewable, and relatively cheap biobased feedstock that has potential in energy, chemicals, and materials. Kraft lignin, more specifically, has been used for more than 100 years as a self-sustaining energy feedstock for industry after which it has finally reached more widespread commercial appeal. Unfortunately, hardwood kraft lignin (HWKL) has been neglected over these years when compared to softwood kraft lignin (SWKL). Therefore, the present work summarizes and critically reviews the research and development (R&D) dealing specifically with HWKL. It will also cover methods for HWKL extraction from black liquor, as well as its structure, properties, fractionation, and modification. Finally, it will reveal several interesting opportunities for HWKL that include dispersants, adsorbents, antioxidants, aromatic compounds (chemicals), and additives in briquettes, pellets, hydrogels, carbon fibers and polymer blends and composites. HWKL shows great potential for all these applications, however more R&D is needed to make its utilization economically feasible and reach the levels in the commercial lignin market commensurate with SWKL. The motivation for this critical review is to galvanize further studies, especially increased understandings in the field of HWKL, and hence amplify much greater utilization.

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Determination of Phenolic Hydroxyl Groups in Technical Lignins by Ionization Difference Ultraviolet Spectrophotometry (∆ε-IDUS method)

Abstract: Abstract

Cited by 21 publications

References 22 publications

Effect of Process Variables on the Solvolysis Depolymerization of Pine Kraft Lignin

Effect of Process Variables on the Solvolysis Depolymerization of Pine Kraft Lignin

Green Modification of Corn Stalk Lignin and Preparation of Environmentally Friendly Lignin-Based Wood Adhesive

Insights into the Potential of Hardwood Kraft Lignin to Be a Green Platform Material for Emergence of the Biorefinery

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